Kretschmer, A., Kirnbauer, A., Frost, R. J. W., Primetzhofer, D., Hans, M., Schneider, J. M., Schuster, R., & Mayrhofer, P. H. (2025). Unprecedented B solubility in cubic (Hf,Ta,Ti,V,Zr)B-C-N coatings. Acta Materialia, 299, Article 121413. https://doi.org/10.1016/j.actamat.2025.121413
The impact of compositional complexity in Ti-B-C-N based coatings was investigated by depositing Ti-rich (Hf,Ta,Ti,V,Zr)B-C-N with varying B/C ratios (from 0/21 to 32/0 at%). Despite a high B content of up to 32 at%, all coatings exhibit a fine-grained columnar single-phase face-centered-cubic (fcc) solid solution without any boride phase. All coatings show similar hardness values of 37−38GPa, but increasing the B content reduces the indentation modulus. Ab initio calculations support this trend in elasticity and confirm the stability of these solid solutions. Despite increasing the compositional complexity, the addition of B and C has little influence on the lattice distortion. Among the coatings, [Figure presented] offers the best combination of high hardness (37.7±1.0GPa) and fracture toughness (Kᵢ꜀=4.0±0.5 MPa*m⁽¹/²⁾). This compositionally complex, single-phase fcc-structured coating retains its hardness – even slightly increasing to 38.3±1.3GPa – upon vacuum annealing to 1200 °C. X-ray diffraction and atom probe tomography confirm its high-temperature phase stability, with phase transformation occurring only above 1200 °C. These results demonstrate the advantages of compositionally complex coatings, which outperform simpler Ti-B-N or Ti-C-N coatings with similar structure, and that the solubility limits can be extended beyond known boundaries by advanced materials science.
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Research facilities:
Röntgenzentrum Universitäre Service-Einrichtung für Transmissionselektronenmikroskopie Vienna Scientific Cluster
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Project title:
201440201-FV02 - P4.4: WP02: Tribological phenomena influenced by additive manufacturing (Tribo3DPrinting) SWP01: 3D printed jurnal bearing with heatpipes: FFG 872176; Vertr.Nr. 201440201-FV02 (FFG - Österr. Forschungsförderungs- gesellschaft mbH) 2201220502-FV02 - P2.2: WP05: Tribological behaviour of High Entropy Nitride Coatings "HENiCoat" SWP02: DFT and Data Science guided multielement-alloy discovery: FFG 872176 - 201220502-FV02 (FFG - Österr. Forschungsförderungs- gesellschaft mbH) 242490201-FV01: Safe and sustainable materials and chemicals for tribosystems WP02: Replacement of critical raw materiasl in material design -SWP01: Development of materials solutions with reduced product carbon footprints and enhanced performance: FFG-Nr. 906860 / Vertr.Nr. 242490201-FV01 (FFG - Österr. Forschungsförderungs- gesellschaft mbH) 242480501-FV01: Lab-to-field environment for Co2 neutral energy systems; WP05: H2 resistant materials and barrier coatings; SWP01: Tribological and mechano-chemical characterization of advanced coatings in exteme environments: 906860 (FFG - Österr. Forschungsförderungs- gesellschaft mbH)
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Project (external):
German Research Foundation Swedish Research Council
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Project ID:
DFG SCHN 735/47– 1 VR-RFI-2019-00191
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Research Areas:
Special and Engineering Materials: 40% Surfaces and Interfaces: 30% Structure-Property Relationsship: 30%